PHOTOSYNTHETICA

Photosynthetica 2010, 48(3):417-420 | DOI: 10.1007/s11099-010-0054-z

Increase of the expression and activity of ferredoxin-NADP⁺ oxidoreductase in the cells adapted to low CO₂ in the cyanobacterium Synechocystis 6803

Y. R. Liu^1,*, W. M. Ma², H. L. Mi^3,*

¹ College of Life Sciences, Fujian Normal University, Fuzhou, China

² College of Life and Environment Sciences, Shanghai Normal University, Shanghai, China

³ National Laboratory of Plant Molecular Genetics, Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai, China

To investigate the effect of low CO₂ on the expression and activity of ferredoxin-NADP⁺ oxidoreductase (FNR) and this enzyme-mediated cyclic electron flow around photosystem I (cyclic PSI), the activity staining, immunoblotting and initial rate of P₇₀₀ ⁺ reduction were measured in high- or low-CO₂-grown (H or L)-cells of wild-type Synechocystis sp. strain PCC 6803 (WT) and its ΔndhB mutant (M55). Major results were depicted as follows. (1) The protein levels and activity of FNR were remarkably stimulated in L-cells of both WT and M55 relative to that in their H-cells. (2) The rate of cyclic PSI was significantly increased in L-cells of WT, not M55, when compared to that in respective H-cells. (3) N-ethylmaleimide, an inhibitor of FNR, partially inhibited the increase in the rate of cyclic PSI induced by low CO₂ in both WT and M55. These findings indicated that low CO₂ enhanced the expression and activity of FNR and the cyclic PSI mediated by FNR. The contribution of FNR to cyclic PSI is shortly discussed.

Additional key words: expression and activity; ferredoxin-NADP⁺ oxidoreductase; low CO₂; Synechocystis 6803

Received: July 24, 2009; Accepted: May 18, 2010; Published: September 1, 2010  Show citation